I suggest you ...

Meet accessibility criteria

Color
– Link text – green link text on white background provides insufficient contrast (NOTE: this issue is caused by the theme rather than the plugin per se) (Hemingway theme).
– On the “Welcome” page, on the video, the headings lack sufficient color contrast (blue text on black).
– On the “Add New Event” page, in the “Date & Time” section, the hint appears to lack sufficient color contrast (light gray on white).
– On the “Tags” page, the “Add New Tag” button seems to provide insufficient color contrast (white text on blue).
– On the “Event Settings” page, for the Events URL slug, the link seems to provide insufficient color contrast (blue text on gray).
– On the “Event Settings” page, for the Single events URL slug, the link seems to provide insufficient color contrast (gray on gray).
– On the “Event Settings” page, the “save changes” button seems to provide insufficient color contrast (white text on blue).
– On the “Event Settings” page, the tooltip descriptions seem to provide insufficient color contrast (gray on gray).
– On the “Event Settings” page, for the “Display” tab, descriptions for the radio button options provide insufficient color contrast (gray on gray).
– On the “Help” page, in the systems information section, the blue text on the black background lacks sufficient color contrast.

Buttons
– On the “Ad New Event” page, in the “Time & Date” section, it does not seem possible to tab to the start time/date.
– Suggest removing all tabindex attributes off fields.

Headings
– iframe for map lacks a “title” attribute.
– On the “Welcome” page, the headings should be sequential. Currently, headings are jumping from H2 to H4 without a H3.
– On the “Add New Event” page, in the “The Events Calendar” section, the headings do not appear to be sequential. They jump from H2 to H4 without a H3.
– On the “Help” page, the page seems to be missing a H1 element.

Input Fields
– On the “Welcome” page, in the “Newsletter signup” section, the INPUT element for the email seems to be lacking a LABEL.
– On the “Add New Event” page, the main TEXTAREA appears to lack a LABEL.
– On the “Event Settings” page, numerous (12) INPUT fields lack LABEL elements.
– On the “Event Settings” page, for the “Display” tab, numerous INPUT fields lack LABEL elements.
– On the “Event Settings” page, for the “APIs” tab, the text INPUT field lacks a LABEL element.
– On the “Event Settings” page, for the “Imports” tab, the “Disable Event Aggregator imports” checkbox lacks a LABEL element.

Other
– On “Welcome” page, the iframe for the video lacks a TITLE attribute.
– On the “Welcome” page, the video does not have captions/audio descriptions.
– On the “Event Settings” page, for the “Display” tab, iframes lack TITLE attributes.
– On the “Event Settings” page, for the “Licenses” tab, the a number of links are not descriptive.